Question: $9qr + 3qs - 9q - 7 = -10r - 6$ Solve for $q$.
Answer: Combine constant terms on the right. $9qr + 3qs - 9q - {7} = -10r - {6}$ $9qr + 3qs - 9q = -10r + {1}$ Notice that all the terms on the left-hand side of the equation have $q$ in them. $9{q}r + 3{q}s - 9{q} = -10r + 1$ Factor out the $q$ ${q} \cdot \left( 9r + 3s - 9 \right) = -10r + 1$ Isolate the $q$ $q \cdot \left( {9r + 3s - 9} \right) = -10r + 1$ $q = \dfrac{ -10r + 1 }{ {9r + 3s - 9} }$